Surprising because a lot of crypto groups use telegram for the exact reason of privacy, but it seems
that's not the case.
Don't wanna plagiarize so read the full story here:
http://anonhq.com/edward-snowden-warns-whatever-dont-use-telegram-messenger-app/
Probably a good idea not to listen to the guy hiding in a country filled with state sponsored hackers. Just a thought.
The biggest 'hackers' where I am from are the NSA and the CIA monitoring everyone against their knowledge or will - federally sponsored :) Here are a list of few of the important things that Edward Snowden brought to light to warn us of a big brother police state and various other things, all proven to be true.
http://mashable.com/2014/06/05/edward-snowden-revelations/#j0L35TJBAPq8